Muscular System
Post on 24-Feb-2016
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Muscular System
• Muscles use chemical energy to exert a pulling force
• Many functions– Movement of body
parts– Propel body fluids
and food– Heartbeat– Distribute heat– Protects body
Muscular System
• Smooth Muscle
• Cardiac Muscle
• Skeletal Muscle
Types of Muscle
• Peristalsis, vasoconstriction• No Striations• Single nucleus• No Transverse Tubules• No Intercalated Discs• Involuntary• Tapered
Smooth Muscle
• Heartbeat• Striations• Single nucleus• Transverse Tubules• Intercalated Discs• Involuntary• Branched
Cardiac Muscle
• Movement of bones at joints• Striations• Multiple nuclei• Transverse Tubules• No Intercalated Discs• Voluntary• Non-Branched
Skeletal Muscle
• Skeletal muscles act as levers
• Levers are simple mechanical devices consisting of a– Rod– Fulcrum– Weight (Resistance)– Force Applied
Levers
• Fulcrum located between resistance and force• Ex. Extending the arm at the elbow
1st Class Lever
• Resistance located between fulcrum and force• Ex. Opening mouth at mandible
2nd Class Lever
• Force located between resistance and fulcrum• Ex. Flexing arm at the elbow
3rd Class Lever
• Origin – The head of the muscle, usually superior, relatively immobile
• Insertion – The end of the muscle, usually inferior, relatively mobile
• When a muscle contracts, the insertion is moved towards the origin
Features of Muscle
• Agonist – A muscle that causes an action– Ex. Deltoid is the agonist for abduction of arm
• Antagonist – A muscle that opposes an action– Ex. Pectoralis Major is the antagonist for
abduction of arm• Synergist – Muscles that work together• Prime Mover – The muscle that does most of
the work in synergistic relationships
Muscle Interactions
• Flexion – Moving parts at a joint, angle decreases
• Extension – Moving parts at a joint, angle increases
• Hyperextension – Extension beyond anatomical position
Types of Movements
• Dorsiflexion – Moving ankle closer to shin• Plantar Flexion – Moving ankle further from
shin
• Abduction – Moving a body part away from the midline of the body
• Adduction – Moving a body part towards the midline of the body, think ADDuction= ADDing to body
• Medial Rotation – Turning a limb on its axis towards the midline of the body
• Lateral Rotation – Turning a limb on its axis away from the midline of the body
• Circumduction – Moving a body part so that it follows a circular path
• Pronation – Rotation of forearm so that the palm is facing downward
• Supination – Rotation of forearm so that the palm is facing upward, think “holds soup”
• Eversion – Turning the foot so the bottom faces laterally
• Inversion – Turning the foot so the bottom faces medially
• Protraction – Moving a body part forward• Retraction – Moving a body part backward
• Elevation – Raising a part of the body• Depression – Lowering a part of the body
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